Method of and apparatus for preparing printing surfaces



Jan. 26, 1937. v E. s. BALLARD 2,069,001

METHOD OF AND APPARATUS FOR PREPARING PRINTING SURFACES Filed Feb. 25,1935 "4. //////////////////////l7///////7////////////////////J.j N

46 r V M SWWMZ Patented Jan. 26, 1937 UNITED STATES PATENT OFFICE ErnestS. Ballard, Berkeley, Calif.

Application February 25, 1935, SerialNo. 8,191

20 Claims.

The present invention relates to the preparation of printing surfacesand more particularly to novel methods of and apparatus for accuratelyreproducing an image on a printing surface whereby designs may betransferred accurately and without distortion from a master cylinder tocylinders to be etched for textile, wall paper and other intaglioprinting purposes.

Prior to my present invention it has been impossible to effect anaccurate transfer by offset printing methods of a continuous image ordesign from the surface of a master cylinder to the surface of a secondcylinder with sufficient accuracy to provide an intaglio printingsurface. 15; The prior methods and apparatus used in offset printing forthe transfer of images from one cylinder to another fail to transfer theimage sufflciently accurately for intaglio printing of continuous imagessince they do not preserve the image in its original form duringtransfer operations and do not match the edges of the transferredimages.

In. the prior art offset printing transfer methods, direct transfer byrolling contact is used from the master cylinder to a rubber transfercylinder from which the image is transferred tothe printing cylinder byrevolving contact of the transfer and printing cylinders. As the lengthof the image on the master surface cannot in practice be made exactlythe same as the cylinder to which the image is to be transferred, sincevery slight differences in diameter are sufficient to destroy thetransfer accuracy for intaglio purposes, and very slight slippage withcylinders .of exactly the samesize will also destroy the accuracy of theimage, the prior transferred images are distorted and fail to meetaccurately at the edges and are not continuous. Efforts to secureaccurate meeting of the edges of the designs transferred by the priorart methods have been made by introducing slippage between the surfacesduring transfer of a design. Efforts have also been made to use theprior art offset printing methods and apparatus to overcome theinaccuracy in the meeting of the edges of the transferred designs inorder that they may be used for intaglio printing, transferring thedesigns to a rubber blanket by rolling contact, and thereafterattempting by painful hand work to stretch the blanket to conform inlength with the circumference of the intaglio cylinder to which theimage is to be transferred.

It will be appreciated that these prior efforts involving slippagebetween surfaces as transfer is effected or the stretching of a transferelement are not adapted to any but very crude intaglio printing work, ifacceptable at all, and both' methods result in material distortion ofthe images during the transfer operations. The prior methods of transferof images have therefore been applied only to offset printing, and cannot be successfully used for the transfer of half tone and like designsfrom a master cylinder to cylinders to be etched for high grade andaccurate intaglio printing reproduction of continuous images.

The methods and apparatus of the present invention successfully overcomethe two major difficulties of the prior art pointed out above andprovide for perfect transfer of images or designs of whatever nature andunder all conditions, whereby the offset method of transfer may for thefirst time be commercially applied to the production of accuratelyetched high grade intaglio printing cylinders having continuous images,as well as for high grade lithograph and other printing of continuousimages.

Accordingly it is a primary object of the present invention to provide anovel method and novel apparatus for effecting accurate transfer of animage without distortion, slurring or degrading of tone values from onesurface to another, whereby the surface which finally receives the imageor design is ready for use as a printing surface or is ready for furtherpreparation such as etching to provide an intaglio or other kind ofprinting surface.

A further object of the present invention is to provide a method andapparatus for effecting accurate transfer of images or designs from asurface bearing the desired image or design to another surface to beused for printing purposes, involving the use of an expansible elasticmem her to accomplish an intermediate step in the transfer process.

Another object of the present invention is to provide a method involvingas a step the novel procedure of transferring a design to or from thesurface. of a rigid member by employing the surface of an elastic memberto effect the transfer by direct uniform contact.

A still further and major object of the present invention is to providefor the first time a method and apparatus for effecting accuratetransfer of a. continuous image or design from the peripheral surface ofa master cylinder to the surface of a secondary cylinder of the same orslightly different size. This I accomplish by direct and. uniformcontact with the concave cylindrical surface of an expansible element.

Still another object of the present invention is to provide a novelapparatus whereby the image transfer methods disclosed herein may bereadily and effectively carried out.

A still further object of the present invention is to provide anapparatus to be employed in the transfer of images or designs, the saidapparatus comprising expansible means having a surface adapted to bebrought into uniform contact with the surface of a rigid member wherebythe two surfaces will be coextensive with each other during the time ofcontact between them.

Other and more specific objects of the present invention will appear inthe following disclosure of a preferred embodimentof my invention andfrom the terms of the appended claims.

Referring to the drawing in which like reference characters indicatelike parts:

Figure 1 is a view in longitudinal section through an apparatusdiagrammatically illustrated for carrying out image transfer operationsin accordance with my invention.

Figure 2 is an end view of the form of apparatus shown in Figure 1.

Figure 3 is a more or less diagrammatic illustration of essentialapparatus for carrying out the steps of the preferred method oftransferring images or designs.

Figure 4 is a view similar to Figure 3 illustrating the apparatus inanother stage of its operation.

Figure 5 is a view in elevation of a portion of the apparatusillustrated in Figures 3 and 4.

In the description which is to follow, it will be understood that theterm image applies to any figure or design comprised of lines or apattern of half tone dots formed in or on the surface of a member, forexample, a master cylinder, by a photographic process or by hand ormachine tracing or engraving. While the embodiment selected for purposesof illustration discloses a process and apparatus for effecting transferof a continuous image or design from a master cylinder to a cylindricalprinting form, it will be understood that the invention is not limitedto transfer of images under these conditions. Also it will be understoodthat transfer of the image to the printing form may be in ink,asphaltum, lacquer or any other transfer medium capable of resistingmordants whereby the resulting transferred image will be acid resistingfor the purpose of etching. The image transferred to the printing formmay also be used for lithographic or other offset printing or may beetched in intaglio.

Referring now to the drawing in which Figures 3 and 4 illustrate thepreferred method of conveying or transferring an image from the surfaceof one cylinder to another, the numeral l indicates an intermediatetransfer means which is illustrated more in detail in Figures 1 and 2.The transfer means I0 is a very important feature of my presentinvention and comprises a member ll of generally tubular form which iscomposed of rubber or a like elastic and expansible material. The memberi4 is provided with annular extensions I 6 of decreased thickness whichare more flexible and yielding than the main body portion and thedecrease in thickness provides guide shoulders I! at each end of themain body portion. The member i4 is mounted in a holder comprising amember I8 preferably of metal which is capable of withstanding fluidpressure applied against its interior wall. In the embodi ment shown,the member I is concentrically mounted in the member l8 which isofacylindrical form for convenience. The inner wall of the cylinder I8is spaced from the outer peripheral surface of the member I 4 to providean annular chamber i9 which is concentric with the member I and thecylinder I8. A suitable conduit connection 2| adapted to be placed incommunication both with a source of fluid pressure and of negative gaugepressure, as demanded by transfer operations, is carried by the cylinderl8 and communicates with the chamber IS.

The annular extensions i6 serve to secure the flexible body l4concentrically in position in the cylinder I8 and this is accomplishedby rings 22 and 23 between which each of extensions l6 are secured. Therings 22 and 23 form a fluid tight seal at each end of the device In andthe entire assembly is held in place by means of cover plates 24 and 28.Suitable securing means such as studs 21 are circumferentially spacedabout the ends of the member I0 and serve to secure the cover plates inposition.

From the foregoing description of the intermediate transfer device itwill be seen that as a suction or negative gauge pressure is appliedwithin the chamber IS, the body portion of the member l4 will expand asshown in Figure 4 causing its inner concave surface to increase indiameter. It should be noted that this diametrical increase is theresult of a uniform radial expansion occurring throughout the entirelength of the main body portion of the member l4. When fluid pressure isapplied to the chamber [9, the body portion of the member i4 willcontract as shown in Figure 3 and this contraction, being uniformthroughout the length of the member I4, its inner surface will moveradially and in a uniform manner. During expansion and contraction ofthe member H, the extensions i6 flex as shown in Figures 3 and 4 of thedrawing and the radially extending faces I! serve as guides incooperation with the inner faces of the rings 23.

Expansion and contraction of the member it may be effected by mechanicalmeans rather than by the hydraulic or pneuma ic means disclosed,however, I prefer to employ hydraulic or pneumatic means.

In carrying out my process of transferring an image from one surface toanother I preferably mount the intermediate transfer means or device 10just described in holders 28 (Figure which are secured to a sliding base29 which is slidable on wings or guides 30 formed on a bed plate or likebase member 3i. The holders 28 are or may be adjustable to accommodatethe device It in different sizes or a series of holders 28 of assortedsizes may be provided. As illustrated, each holder 28 may comprise apedestal having branching arms 32 which form a cradle 33 within whichthe device rests. A clamp 34 fits over the device ID as it rests in thearms 32 and is clamped over the device i0 and to the arms 32 by means ofbolts 38.

The cylinder 38 which may be a master cylinder bearing the design to betransferred or a printing form adapted to receive the design is mountedon an arbor or shaft 39 between centers formed on the bar 4| and theaxially adjustable bar 42. The bars I and 42 are carried by pedestals l3and 44 respectively, which are secured to the base 45. Axial adjustmentof the bar 42 is provided for by having threads formed thereon whichengage within a threaded hole in the pedestal 44. A hand wheel 46provides for turning the bar 42 within the pedestal whereby it may bemoved axially in either direction to clamp or release of means in oneform for carrying out my invention.

In operation of the apparatus to effect transfer of images by themethods disclosed herein, a master cylinder bearing the design in anyone of the coating or transfer mediums previously referred to is securedto a suitable arbor 39, or

if it is already mounted on a shaft, the said shaft or arbor is clampedbetween the centers on the rods II and 42. During this operation theintermediate transfer device l0 occupies the position illustrated inFigure 4 of the drawing. The rubber member I4 is expanded by placing theconduit connection 2| in communication with a source of vacuum whichexhausts the air from the annular chamber l8 causing the body portion ofthe member I to expand whereby its internal diameter is increaseduntilit is slightly larger than the external diameter of the cylinder38. While the mere lowering of the pressure in the annular chamber willaccomplish contraction of the member I4, I flnd that if the space isfilled with a liquid such as water, one stroke of a pump operating inthe water-filled circuit will distend the member II and this action ismore decisive and the expansion more uniform. The circuit is preferablyso arranged that when the water is withdrawn a vacuumis created inchamber It. The device Iii is next moved to the left as viewed on thedrawing to the position illustrated in Figure 3 so that the member llsurrounds the cylinder 38. It will be understood that negative gaugepressure or a vacuumis maintained in the chamber 13 so as to keep theconcave surface of the member l4 spaced from the surface of. thecylinder 38 to avoid blurring of the image.

With the cylinder 38 in position within the device lll, water or fluidunder pressure is forced into chamber l 8. The fluid with a suitablesource of fluid under pressure is relatively heavy and is preferably inthe neighborhood of three hundred pounds per square inch. Also a liquidis preferably employed to exert this pressure. The member I is therebyforced to contract radially at all points so that it presses upon thesurface of the cylinder 38 with a uniform pressure and without slippageof the surfaces at any point of contact. This uniform pressure resultsin an accurate transfer of the image on the surface of the cylinder 38to the concave surface of the member El. As the surfaces of the cylinder38 and the member II are exactly coextensive when they are in contactand as contact occurs at all points simultaneously the transfer iseffected without distortion. That is to say all of the elements of thedesign bear the same relationship to each other after transfer iseffected as in the original design provided on the cylinder 38. Thisundistorted relationship of the component parts of the design continuesduring subsequent uniform expansion of the member H which isaccomplished by release of pressure and again exhausting the air fromthe annular chamber ll. With the rubber cylinder in the distendedposition, the member III is moved to the right as viewed in the drawingpermitting the cylinder 38 to be removed.

The image which now exists by transfer on the rubber member ll may betransferred to a blank printing form which is substituted for the mastercylinder 38. This is accomplished by substantially repeating the stepsof the operation described above, namely shifting the member III to theleft and releasing the vacuum and applying fluid pressure within thechamber l8. Immediate transfer of the image on the surface of the memberH to the blank surface of the printing cylinder occurs and this transferis accomplished without distortion for the reasons set' forth above.Removal of the printing cylinder is accomplished by releasin Pressurewithin the chamber Hi, again exhausting the air or fluid from the saidchamber, shifting holder 28 to the position shown in Figure 4 andremoving the form.

As soon as the transfer medium has dried or been properly treated tomake it more resistant, the surface of the printing cylinder can beetched for printing or if' a transfer medium suitable for the purpose isemployed, the printing cylinder can be used directly for lithographicprinting.

It is to be especially noted that the transfer method described isparticularly adapted for the transfer of designs which are continuousabout the surface of the master cylinder 38 and in fact it is the onlyknown method by which transfer of continuous designs can be successfullyaccomplished that are suitable for use in commercial intaglio wallpaper, textile, and like printing operations. Such designs must notoverlap at their, ends nor have their edges spaced apart by even a veryslight amount when they are transferred to a printing cylinder or otherprinting member which is circular in cross section, and there must be nodistortion of the transferred image. The uniform contraction of therubber tube and simultaneous contact established between the surface ofthe rubber tube and the master cylinder and the rubber tube and theprinting cylinder makes it possible to transferthe continuous unbrokenimage from one cylinder to another without distortion -of the imageparts with relation to each other. It should also be noted in thisconnection that transfer of continuous images may be effected perfectlyeven though the cylinder from which the transfer is made is slightlylarger or smaller in diameter than the cylinder which is to receive thetransferred image. This is important in color printing where perfectregister of superimposed images is necessary. By employing the methodsof the present invention, the several master color cylinders may lackuniformity as to circumference, but the transferred images if conveyedto cylinders of the same diameter will register perfectly in printing.Any necessary adjustment takes place automatically in the contraction orexpansion of the rubber cylinder. This adjustment occurs when the rubbercylinder contracts upon the exterior surface of a cylinder of fixeddiameter and at the instant that this adjustment is effected, thetransfer takes place by contact, and the adjustment halts at the momenttransfer by contact begins.

From the foregoing description of the methods and apparatus of thepresent invention it will be seen that they are adapted foruse.generally where transfer operations are to be carried out and alsothat transfer operations which were heretofore impossible can be readilyaccomplished.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

l. A method of preparing a printing surface by use of an apparatusembodying an elastic transfer member which comprises the steps ofapplying a transfer coatin'g on a master surface bearing the desiredimage, bringing the surface of the elastic transfer member into contactwith said master surface by the direct application of fluid pressurethereto to cause a uniform simultaneous transfer of said entire coatingto the surface of said elastic member, separating said surfaces andthereafter bringing the surface of said elastic member carrying thetransferred image into contact with the surface to be prepared by thedirect application of fluid pressure thereto to cause the uniformsimultaneous transfer of said coating substance to said printingsurface.

2. The method of preparing a printing surface for etching by use ofapparatus embodying an elastic transfer member which comprises the stepsof applying a mordant resisting transfer coating to the printing areasof an image on a master surface bearing the image to be reproduced onsaid printing surface, bringing the surface of an elastic member intocontact with said master surface, separating said surfaces andtransferring said coating thereto, and thereafter bringing the coatedsurface of said elastic member into contact with the surface to beprepared for etching said first and second transfer steps beingaccomplished by the application of fluid pressure to said elastic membernormal to said surfaces and uniform at all points of said surfaces incontact, thereby causing an accurate simultaneous transfer of saidcoating substance to the surface to be etched.

3. The method of transferring an image from a surface bearing the imageto the surface of a printing member comprising the steps of firsttransferring the image from said first named surface to the surface ofan elastic member, and thereafter transferring the image reproduced onsaid elastic member to the surface of a printing member, said transfersteps being carried out by inflating said elastic member so that itssurface approaches and comes into intimate contact with each of saidsurfaces in turn.

4. The method of preparing a series of printing cylinders all of thesame diameter for printing superimposed images in accurate register,comprising the steps of producing an image on each one of a series ofmaster cylinders of substantially the same or different diameters,transferring the image on one master cylinder to a self adjustingtransfer surface and thereafter transferring the image formed on saidself adjusting surface to the surface of one of said printing cylindersby simultaneous application of all points on said surface to the surfaceof one of said printing cylinders, said transfer operation beingrepeated for each master cylinder and its corresponding printingcylinder.

5. An apparatus for effecting transfer of an image from one printingsurface to another comprising an expansible and contractible memberhaving a concave cylindrical surface and means to cause said concavecylindrical surface to assume different diameters.

6. An apparatus for effecting transfer of an image from one printingsurface to another, comprising an expansible and contractible memberhaving a concave cylindrical surface adapted to be brought into contactwith the surface of a printing cylinder or the like to effect transferof an image to or from the said concave cylindrical surface, and meansto cause said concavev cylindrical surface to approach the surface ofsaid printing cylinder and to cause simultaneous contact of saidsurfaces at all points.

7. In an apparatus for transferring images from one surface to another,an elastic transfer member, said member having a concave cylindricalsurface capable of assuming different internal diameters as said memberexpands and contracts.

8. An elastic transfer member of annular form, comprising a body portionand sleeve-like extensions at each end of said body portion adapted tobe secured in mounting means for said member, said extensions being ofless thickness and greater flexibility than said body portion.

9. An apparatus for effecting transfer of an image from one printingsurface to another comprising a transfer device having a concavecylindrical transfer surface, means to cause said surface to assumedifferent internal diameters, means to secure a printing cylinder or thelike with its surface in concentric relationship to said concavesurface, and means for axially separating said cylinder and saidtransfer device.

10. A transfer device comprising a rigid hollow member, an elastictransfer member of sleeve-like form secured in said hollow member andspaced from the interior of said hollow member to provide a chamber, andmeans for varying the pressure in said chamber to cause expansion andcontraction of said elastic member.

11. Apparatus to be employed in the transfer of continuous images ordesigns, comprising a cylinder of rubber secured in a backing of suchsize with respect to the rubber cylinder that an annular space isprovided between the external peripheral surface of the rubber cylinderand the backing, the said space providing for application of fluidpressures at above or below atmospheric pressure to effect radialmovement of all points of the concave interior surface of the rubbercylinder toward and from its center.

12. A cylindrical rubber member to be employed in the transfer of imagesor designs generally of sleeve-like form shaped to encircle a mastercylinder or a printing cylinder and having axial guide shoulders andaxially extending flexible clamping portions extending beyond said guideshoulders.

13. A method of preparing a printing surface by use of an apparatusembodying a surface to be prepared and a master surface of convex shapeformed on members which are circular in cross section and embodying anelastic transfer member adapted to encircle said surfaces in turn andapproach said surfaces solely by radial movement of all points on itssurface which comprises the steps of applying a transfer coating on themaster surface bearing the desired image, bringing the surface of theelastic transfer member into contact with said master surface to cause auniform simultaneous transfer of said entire coating to the surface ofsaid elastic member, separating said surfaces and thereafter bringingthe surface of said elastic member carrying the transferred image intocontact with the surface to be prepared to cause the uniformsimultaneous transfer of said coating substance to said printingsurface.

14. I'he method of preparing a printing surface for etching by use ofapparatus embodying a printing surface and a master surface of convexshape formed on members which are circular in cross section andembodying an elastic member provided with a concave surface adapted toapproach said surfaces in turn solely by radial movement of all pointson the concave surface comprising the steps of applying a mordantresisting transfer coating to the printing areas of an image on saidmaster surface bearing the image to be reproduced on said printingsurface, bringing the surface of said elastic member into contact withsaid master surface, separating said surfaces and transferring saidcoating thereto, and thereafter bringing the coated surface of saidelastic member into contact with the surface to be prepared for etching,said first and second transfer steps being accomplished by theapplication of pressure to said elastic member normal to said surfacesand uniform at all points of said surfaces in contact, thereby causingan accurate simultaneous transfer of said coating substance to thesurface to be etched.

15. An apparatus for effecting transfer of an image from one printingsurface to another comprising a transfer device having a cylindricaltransfer surface, means whereby said device may be placed in spacedconcentric relation with a printing surface, and means to vary thediameter of said transfer surface to contact the same with said printingsurface.

16. An apparatus for effecting transfer of an image from one printingsurface to another comprising means to support a printing surface, meansto support a transfer device in predetermined relation thereto, saiddevice comprising a cylindrical transfer surface, guide means wherebysaid transfer surface may be placed in predetermined spaced concentricrelation to said printing surface, and means to vary the diameter ofsaid transfer surface to contact the same with said printing surface.

17. The method of transferring a surface image to another surface from amember having a deformable wall of sufficient rigidity to normally havea definite conformtion, comprising the steps of arranging the deformablewall substantially in parallelism with said surface that is to receivethe image, and applying pressure fluid directly against said wall todeform it into full and uniform contact with said. surface.

18. The method of transferring an image from the surface of one memberto the surface of another where one of the members is flexible,comprising the steps of arranging said surfaces in proximity whilesubjecting the flexible member to vacuum to maintain the surfaces inseparation, and thereafter destroying the vacuum and bringing saidsurfaces into full intimate contact.

19. In combination, an assembly of parts for effecting the transfer ofprinting images, said assembly comprising an image bearing member, atransfer member having a flexible wall of rather definite inherent shapenormally spaced slightly from the image of the first mentioned memberwhen assembled, and means for applying fluid pressure to said wall tourge it into uniform sur face contact with said image.

20. In apparatus of the character described, a pressure-responsive wallhaving a surface adapted to carry an image, a support for said wall,flexible means for mounting said wall on said support and for guidingsaid wall during its pressure-responsive movements, and means forapplying fluid pressure to said wall.

ERNEST S. BALLARD.

